Header height position control for a cotton harvester

In a self propelled crop harvesting vehicle having a chassis supported on a plurality of ground support wheels, a source of hydraulic fluid and a manual control valve for distribution of said hydraulic fluid, a crop gathering device including header units independently pivoted to said crop gathering device and attached to said crop harvesting vehicle, the improvement comprising:

• a rotary flow divider having a plurality of pump elements interconnected to each other and rotatable synchronously on a common shaft, said rotary flow divider mounted downstream of said manual control valve and providing equalized fluid delivery from each of said plurality of pump elements;
• a plurality of ground variation sensors, one of said sensors associated with one each of said header units;
• a plurality of independent single acting lift cylinders, one of each of said cylinders pivotally mounted between said crop gathering device and one of each of said independently pivoted header units for allowing the raising of said header units responsive to said ground variation sensor;
• a first supply conduit connecting said manual control valve to said rotary flow divider;
• a line check valve in said first supply conduit allowing fluid flow from said manual control valve to said rotary flow divider;
• a plurality of rotary flow divider output ports, one port associated with each one of said plurality of pump elements;
• a plurality of lift cylinder supply lines, one of each supply lines connecting one respective output port of said rotary flow divider to one of said plurality of independent single acting lift cylinders;
• a lift cylinder check valve in each of said lift cylinder supply lines allowing unimpeded fluid flow from said rotary flow divider to each respective single acting lift cylinders;
• a second supply conduit leading from said manual control valve to each of said lift cylinder supply lines;
• a plurality of variable orifice valve assemblies, one of said valve assemblies interposed between each of said lift cylinder supply lines and said second supply conduit, said variable orifice valve assemblies movable responsive to the position of respective said ground variation sensors metering flow to respective lift cylinders whereby said lift cylinder will be supplied with fluid when said ground variation sensor causes said variable orifice to become more restrictive.